The present invention relates to a side cutter to be attached to a sewing machine for facilitating hemstitching by the sewing machine.
Side cutters for facilitating hemstitching by sewing machines have so far been developed, and Japanese Patent No. 2839510 proposes an invention for preventing crosswise run-out of a movable blade in a side cutter. The side cutter 100 has a tabular base plate 1 and a vertical section 1a rising therefrom and is designed to be attached to a sewing machine by fixing a front end portion 2 of the vertical section 1a of the base plate 1 to a presser bar 3 of the sewing machine with a thumbscrew 4, as shown in FIG. 6.
The side cutter 100 has a presser foot 18 attached to the lower side of the base plate 1, a fixed blade 21 attached to a front end portion of the presser foot 18 and a movable blade 23 located above the fixed blade 21. The movable blade 23 cuts cloth in cooperation with the fixed blade 21. The base plate 1 has in its vertical section 1a a working lever 5, which transmits the vertical movement of a sewing machine needle to the movable blade 23 through a lever 13 to be described later.
As shown in FIG. 7, the presser foot 18 supports, in its vertical section 18c formed in the middle thereof, the lever 13 with a supporting shaft 25 so that the lever 13 can swing vertically. Meanwhile, a leaf 26 is attached to a rear end portion 13a of the lever 13. This leaf 26 is brought into plane contact with a lateral side of a vertical section, 18d formed in the rear end portion of the presser foot 18 to urge the lever 13 in the horizontal direction as indicated by the arrow 26a. 
Thus, the movable blade 23, which is fixed to a front end portion 13b of the lever 13, reciprocates vertically pushing the cutting edge of the fixed blade 21 in the horizontal direction indicated by the arrow 26b to cut cloth.
However, the side cutter 100 for a sewing machine involves the problem that the mechanism containing the lever 13, the leaf 26 and the like incorporated to ensure shear force required in cutting cloth by bringing the movable blade 23 into contact with the cutting edge of the fixed blade 21 is complicated and it entails great trouble and cost in manufacturing it.
Meanwhile, operations of attaching and detaching the side cutter 100 to and from the sewing machine are intricate and take much time, since its vertical section 1a of the base plate 1 must be fastened at the front end portion 2 with the thumbscrew 4 to the presser bar 3 of the sewing machine.
The present invention is directed to providing a side cutter for a sewing machine having overcome the problems inherent in the prior art as described above, which is small-sized and simple-structured and yet can securely achieve shearing of cloth and which can be attached and detached to and from a sewing machine speedily and securely.
The gist of the present invention resides in a side cutter for a sewing machine, the side cutter comprising a fixed blade located in front of a frame body; a link frame attached to the frame body so as to transmit a vertical movement of a sewing machine needle to the movable blade; the movable blade being fixed to a lower front end portion of the link frame to cut cloth in cooperation with the fixed blade; the frame body having a holder coupling section to be detachably engaged with a holder and fixed to the sewing machine.
The side cutter for a sewing machine is also characterized in that the holder coupling section has a pair of guides standing on each side respectively and a supporting rod extended between front end portions of the guides and that the holder coupling section is located under the frame body.
The side cutter for a sewing machine is also characterized in that the link frame is attached to the frame body through a spring washer.
The side cutter for a sewing machine is also characterized in that the movable blade is fixed to a front lower end portion of the link frame through a spring washer.
Other aspects and advantages of the invention will become apparent from the following description, taken in conjunction with the accompanying drawings illustrating by way of examples the principles of the invention.